I found out about a glitch that enables you to get on the roof of the south building.
Step 1: Go to the SouthEast corner of the level, but don't go into the building.
Step 2: There is a broken platform hanging down in the air. Jump from the corner towards the yellow railing. When you hit the railing, stop moving. You should just float in mid-air.
Step 3: Move forward, but instead of moving forward, you'll go up.
Step 4: When you get to the top of the platform, head towards the west side of the building.
Step 5: There is another platform, jump onto it. Climb onto the roof and head towards the east.
If you have done this correctly, then Congratulations! You have reached the best sniper spot in the entire level(at least I consider it that). Now you don't have to worry about anyone stealing a care package, or wacking you from behind.